Three-Dimensional (3-D) Imaging with a Row-Column Addressed (RCA) Transducer Array using Synthetic Aperture Sequential Beamforming (SASB)

ABSTRACT

An ultrasound imaging system includes a probe and a console. The probe includes a row-column addressed transducer array, first beamformer configured to beamform echo signals received by the row-column addressed transducer array and produce a set of image planes for each emission with a single focus in both transmit and receive, and a first communication interface. The console includes a second complementary communication interface and a second beamformer configured to beamform the focused set of image planes and produce a three-dimensional volume of ultrasound data.

TECHNICAL FIELD

The following generally relates to ultrasound imaging and moreparticularly to 3-D imaging with an RCA transducer array using SASB.

BACKGROUND

An ultrasound imaging system includes a transducer array with aone-dimensional (1-D) or a two-dimensional (2-D) array of transducingelements. A 2-D transducer array has been employed for 3-D real-timescanning of a volume by arranging the transducer elements in arectangular grid and steering the beam in the lateral and elevationdirections to acquire data of the volume. Where the rectangular grid hasan N×N geometry, the total number of elements is N². To individuallycontrol each of the elements, a direct connection is made to eachelement.

Channel count can be reduced, while maintaining aperture size, through asparse array, in which only a subset of the elements is active at thesame time. However, these arrays have a reduced signal-to-noise ratio(SNR) and introduce higher side lobes and/or grating lobes on severesparseness. This results in degradation of image contrast and constrainsthe diagnostic value of the exam. Another approach includes operatingthe N×N array as an RCA array. For this, the elements are addressedgroup-wise by row and column index, and each row and column of elementsacts as one large element. A fully addressed RCA N×N array would requireonly 2N channels.

However, addressing individual elements or rows and columns of elementsleads to practical challenges in producing the interconnections,sampling, and real-time processing of a large volume of data, and alarge number of wires results in a large cable from the transducer tothe scanner. Hence, there is an unresolved need for an approach thatfurther reduces the number of channels between the probe and the consolefor real-time 3-D imaging, e.g., for probes that transmit data to aconsole using wired and/or wireless technologies.

SUMMARY

Aspects of the application address the above matters, and others.

In one aspect, an ultrasound imaging system includes a probe and aconsole. The probe includes a row-column addressed transducer array,first beamformer configured to beamform echo signals received by therow-column addressed transducer array and produce a set of image planesfor each emission with a single focus in both transmit and receive, anda first communication interface. The console includes a secondcomplementary communication interface and a second beamformer configuredto beamform the focused set of image planes and produce athree-dimensional volume of ultrasound data.

In another aspect, a method includes transmitting an ultrasound signalwith a group of elements of a row-column addressed transducer array ofan ultrasound probe of an ultrasound imaging system, and receiving echosignals with one or more orthogonal groups of elements of the row-columnaddressed transducer array. The method further includes beamforming, inthe ultrasound probe, signals from each group producing a set of imageplanes focused in transmit and receive using synthetic aperturesequential beamforming, and transmitting the set of focused image planesfrom the probe to a console of the ultrasound imaging system. The methodfurther includes beamforming the set of focused image planes to producea three-dimensional volume of the scanned object using syntheticaperture sequential beamforming, and visually displaying thethree-dimensional volume.

In another aspect, a non-transitory computer readable storage medium isencoded with computer readable instructions. The computer readableinstructions, when executed by a processor of a computing system, causethe processor to: receive a set of image planes beamformed in anultrasound probe of an ultrasound imaging system including a row-columnaddressed transducer array, beamform, in a console of the ultrasoundimaging system, the set of focused image planes to produce athree-dimensional volume of the scanned object using synthetic aperturesequential beamforming, and visually display the three-dimensionalvolume.

Those skilled in the art will recognize still other aspects of thepresent application upon reading and understanding the attacheddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The application is illustrated by way of example and not limited by thefigures of the accompanying drawings, in which like references indicatesimilar elements and in which:

FIG. 1 schematically illustrates an example ultrasound imaging system;

FIG. 2 schematically illustrates an example RCA array;

FIG. 3 shows an approach to calculate receive time delays from atime-of-flight path;

FIG. 4 shows example row or column elements, wave propagation, and imageplanes;

FIG. 5 shows a geometrical representation of fixed transmit focal lines;

FIG. 6 shows a geometrical representation of fixed receive focal lines;

FIG. 7 shows a geometry model of emitted wave fields from twoconsecutive emissions; and

FIG. 8 illustrates a method in accordance with an embodiment herein.

DETAILED DESCRIPTION

The following describes a real-time 3-D ultrasound imaging approachusing an RCA array and a beamforming approach based on syntheticaperture sequential beamforming (SASB). In general, the beamforming isdivided into two-stages with different beamformers, one in the probe andone in the console. The first stage (probe) beamformer processes thechannel data from the RCA array and generates a set of B-mode imageplanes using a single focal line in both transmit and receive. This setis transmitted from the probe to the console. The second stage (console)beamformer process this set and generates a whole rectilinear volume.With the low channel count required to transfer the set from the probeto the console, this approach is well-suited for real-time 3-D imagingusing wireless probes and/or high frequency probes.

FIG. 1 schematically illustrates an example system 10, which includes anultrasound imaging system 100.

The ultrasound imaging system 100 includes a probe 102 and console 104.The probe 102 includes a console communication interface (“communicationinterface”) 106, and the console 104 includes a probe communicationinterface (“communication interface”) 108. The illustrated communicationinterfaces 106 and 108 communicate with each other via a communicationchannel 110. In one instance, the communication channel 110 is awireless channel. In another instance, the communication channel 110includes a wire and/or other physical electrical conductor. Thecommunication can be direct or through another device such as over anetwork.

The probe 102 includes a 2-D transducer array 112 configured for RCA.The 2-D array 112 includes a plurality of detector elements 114 arrangedin a N×M matrix of N rows and M columns, where N and M are positiveintegers and N=M or N≠M (e.g., N>M or N<M). Examples of square arraysinclude 64×64, 192×192, 256×256, 512×512 and/or other arrays, includinglarger and/or smaller arrays. Examples also include non-square arrayssuch as rectangular, circular, irregular and/or other shaped arrays. Theelements can be piezoelectric (PZT), capacitive micromachined ultrasonictransducer (CMUT) elements, and/or other transducing elements.

Briefly turning to FIG. 2, an example 6×6 (N=M=6) RCA array 202 isschematically illustrated. Each column 204 includes an electricallyconductive trace 206 in electrical communication with each element 208of the column 204, with an electrode 210 in electrical communicationwith the electrically conductive trace 206. Each row 212 includes anelectrically conductive trace 214 in electrical communication with theelements 208 of the row 212, with an electrode 216 in electricalcommunication with the electrically conductive trace 214. RCAeffectively transforms the 36-element 6×6 2-D array 202 into a 6-element1-D column array 218 and an orthogonal 6-element 1-D row array 220. Thiseffectively reduces the number of element channels from N² to 2N.

A suitable RCA array is described in patent application Ser. No.15/252,632, entitled “Vector Velocity Estimation Using TransverseOscillation (TO) and Synthetic Aperture Sequential Beamforming (SASB),”and filed on Aug. 31, 2016, the entirety of which is incorporated byreference herein. Another suitable RCA array is described in patentapplication Ser. No. 15/468,715, entitled “A Row-Column Addressed Arraywith N Rows and N Columns and With Less Than 2N Electrical Connections,”and filed on Mar. 24, 2017, the entirety of which is incorporated byreference herein. In patent application Ser. No. 15/468,715, a pair of arow and a column share a front-end circuit.

Furthermore, the transducing elements 208 may include integratedapodization, which may be identical or different for the individualelements. An example is described in patent applicationPCT/IB2013/002838, filed Dec. 19, 2013, and entitled “Ultrasound ImagingTransducer Array with Integrated Apodization,” the entirety of which isincorporated herein by reference. Furthermore, the 2-D array 202 mayhave flat 1-D arrays, one curved 1-D array, two curved 1-D arrays, asingle curved lens in front of or behind one of the 1-D arrays, a doublecurved lens in front of or behind the 1-D arrays, a combination of atleast one curved 1-D array and at least one curved lens, etc. An exampleis described in patent application PCT/IB2016/053367, filed Jun. 8,2016, and entitled “Row-Column Addressed 2-D array with a Double CurvedSurface,” the entirety of which is incorporated herein by reference.

In FIG. 2, each row and column may have its own front-end circuit. Forexample, the electrode 210 is in electrical communication with its ownfront-end circuit (not visible), and the electrode 216 is in electricalcommunication with its own front-end circuit (not visible). In avariation, pairs of rows and columns may share front-end circuit, asdescribed in application Ser. No. 15/468,715. With a shared front-endcircuit, the electrodes 210 and 216 are both in electrical communicationwith a same switch (not visible), which switches between the electrodes210 and 216 for transmitting and receiving. The switch can be part ofthe shared front-end circuit and/or separate therefrom. Thisconfiguration further reduces the number of channels from 2N to N.

Returning to FIG. 1, the probe 102 further includes transmit circuitry116 configured to generate a set of pulses that are conveyed to thetransducer array 112. The set of pulses excites a set of the transducerelements 114, which causes the elements 114 to emit ultrasound signals.The probe 102 further includes receive circuitry 118 configured toreceive the electrical signals. The receive circuitry 118 may amplify,filter, convert analog signals to digital signals, and/or otherwisecondition and/or pre-preprocess the signals. An example transmit andreceive sequence for real-time 3-D imaging with the SASB based approachis described in greater detail below.

The probe 102 includes a first stage beamformer 120, which is configuredto process, via delay and sum beamforming, the electrical signals foreach emission using a fixed focus and a single delay-profile, producinga set of B-mode image planes. The focal lines, in one instance, are at asame depth, and, for each emission, a number of focal linesperpendicular to the transmit focal line is created. The first stagebeamformer 120 employs an algorithm, which is based on a SASB. Anexample algorithm for computing the single delay-profile is described ingreater detail below. The set of B-mode image planes is transmitted tothe console 104 via the communication interfaces 106 and 108. Since thefirst stage beamformer 120 calculates only a single set of delay values,the first stage beamformer 120 can be of low complexity. In addition,because of the beamforming, data from all of the column (or row)elements are not transmitted to the console 104, and less than 2Nchannels (or less than N channels when using the RCA of patentapplication Ser. No. 15/468,715) are needed, for creating a 3-D volume.As such, the system 10 is well-suited for real-time 3-D wirelessimaging. Patent application Ser. No. 15/468,715 describes wireless framerates, wireless technologies, and examples of SASB algorithms.

The probe 102 further includes a probe controller (“controller”) 122,which is configured to control the transmit circuitry 116, the receivecircuitry 118, the first stage beamformer 120, and/or the probe wirelesscommunication interface 106. Such control can be based on a current modeof operation (e.g., B-mode, real-time 3-D with SASB, etc.). The probe102 includes a probe user interface (UI) 142. The UI 142 may include aninput device (e.g., a button, a slider, a touch surface, etc.) and/or anoutput device (e.g., a visual and/or audible, etc.).

The console 104 includes a second stage beamformer 124 configured toprocess the set of B-mode image planes produced by the first stagebeamformer 120, producing a number of new image planes to generate 3-Ddata for the entire scanned volume. In a variation, the second stagebeamformer 124 is remote from the imaging system 100, e.g., in aseparate computing device. The console 104 further includes a scanconverter 136 that scan converts the image planes, converting the imageplanes into the coordinate system of a display 138, which visuallydisplays the 3-D data.

The console 104 further includes a console controller (“controller”)140, which is configured to control the communication interface 108, thesecond stage beamformer 124, and/or the scan converter 136. Such controlcan be based on a current mode of operation (e.g., B-mode, real-time 3-Dwith SASB, etc.). The console 104 includes a console user interface (UI)142, which may include an input device (e.g., a button, a slider, atouch surface, etc.) and/or an output device (e.g., a visual and/oraudible, etc.).

It is to be appreciated that the beamformers 120 and 124 and/or othercomponents of the imaging system 100 can be implemented via hardwareand/or a processor (e.g., a microprocessor, central processing unit(CPU), etc.) executing one or more computer readable instructionsencoded or embedded on a computer readable storage medium (whichexcludes transitory medium) such as a physical memory device. Theprocessor can additionally or alternatively execute computer readableinstructions carried by transitory medium such as a carrier wave, asignal, or other transitory medium.

Turning to FIGS. 3-7, a non-limiting example for real-time 3-D imagingusing the RCA 2-D transducer array 112 with the SASB based beamformingis described.

FIG. 3 describes an approach for calculating a delay for the first stagebeamformer 120. In FIG. 3, a sub-portion of the 2-D array 112 is shown.A group 304 of (column or row) elements r_(e) transmits, and a group 306of (row or column) elements r_(r) (orthogonal to the group 304)receives. A transmit focal line 308 is a virtual line source (VLS)emitting a cylindrical wave front spatially confined by an openingangle, and a receive focal line 310 is a virtual line receiver (VLR)receiving scatterers. The VLS and VLR include virtual row and columntransducer elements (VEs).

The focusing delays for the first stage beamformer 120 are computed froma round trip time-of-flight (TOF) through a TOF path, which is apropagation time of an emitted wave in its path from a transmit originof the array 302, to an image point (IP) of interest, and back to areceiver of the array 302. A delay value t_(d) can be calculated asshown in EQUATION 1:

$\begin{matrix}{{t_{d} = \frac{d_{tof}}{c}},} & {{EQUATION}\mspace{14mu} 1}\end{matrix}$

where d_(tof) represents a length of a TOF path 316, and c is the speedof sound. In FIG. 3, for virtual transmit and receive elements {rightarrow over (r)}_(vls) 312 and {right arrow over (r)}_(vls) 314, the TOFis calculated along the path 316 from an emit element {right arrow over(r)}_(e) 318, to the virtual emit element {right arrow over (r)}_(vls)312, to an image point (IP) {right arrow over (r)}_(ip) 320, to thevirtual receive element {right arrow over (r)}_(vlr) 314, and to areceive element {right arrow over (r)}_(r) 322. In this example, theelements {right arrow over (r)}_(e) 318 and {right arrow over (r)}_(r)322 receptively are the elements of the groups r_(e) 304 and r_(r) 306with shortest distances to the virtual elements {right arrow over(r)}_(vls) 312 and {right arrow over (r)}_(vlr) 314.

In this example, the length of the TOF path 316 d_(tof) is calculated asshown in EQUATION 2:

d _(to) =|{right arrow over (r)} _(vls) −{right arrow over (r)} _(e)|±|{right arrow over (r)} _(ip) −{right arrow over (r)} _(vls) |±|{rightarrow over (r)} _(vlr) −{right arrow over (r)} _(ip) |±|{right arrowover (r)} _(r) −{right arrow over (r)} _(vlr)|,    EQUATION 2:

where each operation |.| calculates a length of a vector, and the “±”corresponds to whether the image position (IP) {right arrow over(r)}_(ip) 320 is above or below (as shown in FIG. 3) the VLS or VLR 308and 310. In EQUATION 2, the differences between the individual channeldelays do not change with the image position {right arrow over (r)}_(ip)320 since the term involving the receive elements (|{right arrow over(r)}_(r)−{right arrow over (r)}_(vlr)|) does not depend on {right arrowover (r)}_(ip).

FIG. 4 schematically illustrates focal lines for the first stagebeamformer 120 for three different emissions via three different groupsof elements. It is to be understood that only three emissions are shownfor explanatory purposes, clarity, and sake of brevity. Focal lines forreceive can be similarly explained, but with groups of elementsorthogonal to the illustrated groups of elements and receivingscatterers, and will not be separately shown.

A first group of elements 402 transmits a first cylindrical wave front404, a second group of elements 406 transmits a second cylindrical wavefront 408, and a third group of elements 410 transmits a thirdcylindrical wave front 412. Focused lines 414, 416 and 418 each comprisea plurality samples (each indicated by a “dot”). With fixed focusing,each sample contains information from spatial positions indicated byarcs 420, 422 and 424 of the cylindrical wave fronts 404, 408 and 412.

For a single sample, the information is limited by an opening angle oftwo planes passing through an image point and has a center in the focalline. Each sample contains information from many image points indicatedby the arcs 420, 422 and 424, but only from one common image point(e.g., an image point 426 in FIG. 4), which is where the arcs 420, 422and 424 intersect. In general, a single image point is thereforerepresented in multiple image planes from the first stage beamformer 120obtained from multiple emissions.

FIGS. 5 and 6 respectively represent a geometrical orientation of fourtransmit and receive focal lines for creating a 3-D volume. In oneinstance, the sequence is transmit once with a column (or row) andreceive with one of the rows (or columns), repeat for each receive row(or column), and then repeat for each transmit column (or row). Inanother instance, the sequence is transmit once with a column (or row)and receive with two of the receive rows (or columns), transmit onceanother column (or row) and receive with the other two of the receiverows (or columns), and repeat for the two remaining transmit columns (orrows).

In another instance, the sequence is transmit once with a column (orrow) and receive on all four rows (or columns), and repeat for eachcolumn (or row). In this case, there will be one signal for each receiverow (or column), four signals for each transmit column (or row), andsixteen total signals. That is, the first stage beamforming 120 willgenerate sixteen image planes for this sequence. The probe 102 transmitsthese sixteen signals to the console 104, where they are furtherprocessed with the second stage beamforming 124 to produce a higherresolution volume. Without the first stage beamforming, the probe 102would instead have to transmit all of the channel data.

For example, using a 192+192 λ/2 pitch 3 MHz RCA array, imaging down toa depth of 15 cm for every emission requires 195 μs and considering the192 single element emissions and receiving single element data peremission corresponds to a volume rate of 0.14 Hz. However, transmittingall the receive channel data in parallel back to scanner per emissioncorresponds to a volume rate of 26 Hz. The volume rates can be improvedusing SASB first stage beamforming by transmitting and receiving, forexample, 20 beamformed planes, in this way the volume rate for the casewhere the receive data is transmitted sequentially back to the scannerper emission becomes 12 Hz and for transferring the receive data inparallel per emission back to the scanner, the volume rate becomes 256Hz. The increment in the volume rate acquisition and fewer number ofchannel data transferred back to the scanner can effectively increasethe accuracy by lowering the standard deviation for flow estimation.

The virtual receive planes can be placed with a distance betweencorresponding to the width of the first stage point spread function. Itswidth is given by FWHM=λF#. The F# is defined as the ratio of the VLS orVLR radial distance from the center of the array to the width of theactive aperture. The active aperture can be smaller or equal to thephysical size of the array. The width of the aperture is N λ/2 andassuming a rectangular imaging area, the number of planes needed is:

${m = {\frac{N\; \frac{\lambda}{2}}{\lambda \; F\#} = \frac{N}{2F\#}}},$

where N is the number of elements in each dimension of an RCA array witha λ/2 pitch. Thereby, the reduction ratio can be defined as:

$Q = {\frac{N}{m} = {2F{\#.}}}$

For example, by transferring individual channel data of each receivingelement in parallel, the total volume rate is 27 Hz when using a 192+192RCA array with λ/2 pitch and a center frequency of 3 MHz for imagingdown to a depth of 15 cm. However, by using SASB first stage beamforminginside the probe and placing the fixed VLR sources with an f_(#=)5, thevolume rate can increase up to 10 times, i.e., 270 Hz.

The second stage beamformer 124 constructs a higher resolution sample byselecting a sample from each of the B-mode planes generated by the firststage beamformer 120 that contains information from the spatial positionof the image point and summing a weighted set of these samples. Thesecond stage beamformer 124 constructs a higher resolution image pointat {right arrow over (r)}_(ip)=(x, y, z) as a sum over samples from K(z)contributing emissions as shown in EQUATION 3:

h({right arrow over (r)} _(ip))=Σ_(l=1) ^(L(z))Σ_(k=1) ^(K(z)) W(x_(k) ,z)W′(y _(l) , z)S _(lk)(Z _(lk)),

where W and W′ are dynamic apodization functions, S_(lk) is a spatialsignal from the output of the first stage beamformer 120 for emission kand reception l, and Z_(lk) is a depth of the contributing sample.

W and W′ control the weighting of the contribution from each emissionand reception, and are functions of the axial position z of the imagepoint since the number of contributing emissions and receptions K(z) andL(z) increase with range. The variable Z_(lk) is dependent on thefocusing of the first stage beamformer 120 and can be calculated asshown in EQUATION 4:

Z _(lk) =|{right arrow over (r)} _(vls) _(k) −{right arrow over (r)}_(e) _(k) |±|{right arrow over (r)} _(ip) −{right arrow over (r)} _(vls)_(k) |±|{right arrow over (r)} _(vlr) _(l) −{right arrow over (r)} _(ip)|±|{right arrow over (r)} _(r) _(l) −{right arrow over (r)} _(vlr) _(l)|.

where the sub-indices k and 1 respectively correspond to emission numberk and reception number l.

FIG. 7 shows a geometry model for two consecutive emissions. The VE's ofthe contributing emissions and receptions form synthetic apertures, andK(z) and L(z) are measures of the size of the synthesized aperture.Since K and L increase linearly with range within the boundary of thephysical transducer, they facilitate a range independent lateralresolution. The terms K(z) and L(z) can be calculated as shown inEQUATION 4:

$\begin{matrix}{{{K(z)} = {\frac{D(z)}{\Delta} = \frac{2( {z - z_{v}} ){\tan ( \frac{\alpha}{2} )}}{\Delta}}},} & {{EQUATION}\mspace{14mu} 4}\end{matrix}$

where D(z) is a lateral width of a wave field at depth z, Δ is adistance between two VE's of two consecutive emissions, and a is anopening angle of the VE. The opening angle can be computed as shown inEQUATION 5:

$\begin{matrix}{{\alpha = {2\; {\arctan ( \frac{1}{2\; F\#} )}}},} & {{EQUATION}\mspace{14mu} 5}\end{matrix}$

where

${{F\#} = \frac{z_{v}}{D_{a}}},$

and D_(a) is a size of a sub-aperture. The opening angle α is an angularspan for which a phase of a wave field can be considered constant.

The variable z determines the number of planes from the first stagebeamformer 120 which can be added in the second stage beamformer 124 foran image point at the depth z. In general, the second stage beamformer124 computes a single high resolution image point by extractinginformation from all of the image planes generated by the first stagebeamformer 120 that contain information from that image point.

At greater depth, K(z) will eventually exceed the number of availableplanes from the first stage beamformer 120. At depths beyond this pointthe synthesized aperture will no longer increase with depth and thelateral resolution will no longer be range independent. Furthermore, thenumber of emissions that can be applied in the sum in EQUATION 3decreases as the lateral position of the image point moves away from thecenter. The synthesized aperture decreases for image planes near theedges, and the lateral resolution is, thus, laterally dependent.

Grating lobes arise at a combination of a sparse spatial sampling andwave fields with large incident angles. The input to the second stagebeamformer 124 are the image planes from the first stage beamformer 120,and the construction of these planes impacts grating lobes. The VE'sfrom a virtual array and the distance (Δ) between the VE's determines alateral spatial sampling. The range of incident angles to the virtualarray can be determined by the opening angle α of the VE.

By restricting a, a sample of image line produced the first stagebeamformer 120 only contains information from wave fields with incidentangles within α. The grating lobes can be avoided by adjusting either ofthese parameters. If λ=c/f₀, where f₀ is a center frequency, the narrowband condition for avoiding grating lobes can formulated as shown inEQUATION 6:

$\begin{matrix}{{F\#} = {\frac{\Delta}{\lambda/2}.}} & {{EQUATION}\mspace{14mu} 6}\end{matrix}$

The above is described for fixed focal lines. It is to be understoodthat the above can also be utilized with focal lines dynamically focusedat each depth. For example, the above may include microbeamforming forRCA arrays, which allows for focal lines that are not fixed and can bedynamically focused at each depth. Examples of micro beamforming aredescribed in WO/2002/017298, entitled “Ultrasonic diagnostic imagingsystem with dynamic microbeamforming,” and filed Aug., 23, 2001,US20080262351 A1, entitled “Microbeamforming Transducer Architecture,and file Sep. 22, 2005, and US20140121521 A, entitled “Two dimensionalultrasonic diagnostic imaging system with two beamformer stages,” andfiled Jun. 28, 2012.

FIG. 8 illustrates a method in accordance with an embodiment(s)described herein.

It is to be understood that the following acts are provided forexplanatory purposes and are not limiting. As such, one or more of theacts may be omitted, one or more acts may be added, one or more acts mayoccur in a different order (including simultaneously with another act),etc.

At 802, the RCA array 112 is controlled to transmit ultrasound signals,as described herein.

At 804, the RCA array 112 is controlled to receive echo signals producedin response thereto, as described herein.

At 806, the first stage beamformer 120 in the probe 102 processes thereceived signals, generating a set of B-mode image planes, as describedherein.

At 808, the probe 102 transfers the set of B-mode image planes to theconsole 104, as described herein.

At 810, the second stage beamformer 124 in the console 104 or othercomputing device processes the set of B-mode image planes, generating a3-D image volume, as described herein.

The 3-D image can be visually presented, stored, transferred to anotherdevice, manipulated, etc.

The methods described herein may be implemented via one or moreprocessors executing one or more computer readable instructions encodedor embodied on computer readable storage medium (which excludestransitory medium) such as physical memory which causes the one or moreprocessors to carry out the various acts and/or other functions and/oracts. Additionally, or alternatively, the one or more processors canexecute instructions carried by transitory medium such as a signal orcarrier wave.

The application has been described with reference to variousembodiments. Modifications and alterations will occur to others uponreading the application. It is intended that the invention be construedas including all such modifications and alterations, including insofaras they come within the scope of the appended claims and the equivalentsthereof.

What is claimed is:
 1. An ultrasound imaging system, comprising: aprobe, including: a row-column addressed transducer array; a firstbeamformer configured to beamform echo signals received by therow-column addressed transducer array and produce a set of image planesfor each emission with a single focus in both transmit and receive; anda first communication interface; and a console, including: a secondcomplementary communication interface; and a second beamformerconfigured to beamform the focused set of image planes and produce athree-dimensional volume of ultrasound data.
 2. The system of claim 1,wherein the first beamformer beamforms the received echo signals with analgorithm that is based on synthetic aperture sequential beamforming. 3.The system of claim 1, wherein the second beamformer beamforms thefocused set of image planes with an algorithm that is based on syntheticaperture sequential beamforming.
 4. The system of claim 1, wherein thefirst and second complementary communication interfaces include wirelessinterfaces, and the first communication interface wirelessly transmitsthe set of image planes, which are wirelessly received by the secondcomplementary communication interface.
 5. The system of claim 1, whereinthe row-column addressed transducer array includes an N×N matrix ofelements, where N is a positive integer, and less than 2N channels. 6.The system of claim 1, wherein the row-column addressed transducer arrayincludes an N×N matrix of elements, where N is a positive integer, andless than N channels.
 7. The system of claim 1, wherein the row-columnaddressed transducer array transmits with one group of elements creatinga focused transmit line, and receives with one orthogonal group ofelements creating an orthogonal focused receive line.
 8. The system ofclaim 1, wherein the row-column addressed transducer array transmitswith one group of elements creating a focused transmit line, andreceives with two or more orthogonal groups of elements creating two ormore orthogonal focused receive lines.
 9. The system of claim 1, whereineach sample in an image line contains information from a set of spatialpositions, and the second beamformer produces an image point by summingonly samples, from the sets of the image planes that contribute to theimage point.
 10. The system of claim 1, wherein each sample in an imageline contains information from a set of spatial positions, and thesecond beamformer produces an image point by summing a weighted set ofsamples, from the sets of the image planes that contribute to the imagepoint.
 11. The system of claim 1, wherein each sample in an image linecontains information from a set of spatial positions, and the secondbeamformer produces an image point by summing over samples from multiplecontributing emissions and receptions.
 12. The system of claim 1,wherein the three-dimensional volume of ultrasound data is a real-timeimage.
 13. A method, comprising: transmitting an ultrasound signal witha group of elements of a row-column addressed transducer array of anultrasound probe of an ultrasound imaging system; receiving echo signalswith one or more orthogonal groups of elements of the row-columnaddressed transducer array; beamforming, in the ultrasound probe,signals from each group producing a set of image planes focused intransmit and receive using synthetic aperture sequential beamforming;transmitting the set of focused image planes from the probe to a consoleof the ultrasound imaging system; beamforming, in the console, the setof focused image planes to produce a three-dimensional volume of thescanned object using synthetic aperture sequential beamforming; andvisually displaying the three-dimensional volume.
 14. The method ofclaim 13, wherein the row-column addressed transducer array includes anN×N matrix of elements, and the transmitting includes transmitting lessthan 2N focused image planes to generate the three-dimensional volume.15. The method of claim 13, wherein the row-column addressed transducerarray includes an N×N matrix of elements, and the transmitting includestransmitting less than N focused image planes to generate thethree-dimensional volume.
 16. The method of claim 13, wherein eachsample in an image line contains information from a set of spatialpositions, and the beamforming the set of focused image planes includescombining only samples that contribute to the image point.
 17. Themethod of claim 16, wherein a number of the focused image planes of theset of focused image planes beamformed to generate the image pointdepends on a depth of the image point.
 18. The method of claim 16,wherein the beamforming the set of focused image planes includes summingthe samples over all emissions and receptions.
 19. The method of claim16, wherein the number of emissions and receptions increase with range.20. A non-transitory computer readable storage medium encoded withcomputer readable instructions, which, when executed by a processor of acomputing system, cause the processor to: receive a set of image planesbeamformed in an ultrasound probe of an ultrasound imaging systemincluding a row-column addressed transducer array; beamform, in aconsole of the ultrasound imaging system, the set of focused imageplanes to produce a three-dimensional volume of the scanned object usingsynthetic aperture sequential beamforming; and visually display thethree-dimensional volume.